My STBXAH finally agreed to Soberlink testing 3 times/day on the days he has custody of our children (which is every other week). It took a couple of sessions with a mediator and a couple with a co-parenting therapist, and me pleading with him, pointing out that this is the one issue on which I'm fighting him and going to continue fighting him, before he finally agreed.
I just wanted to add that STBXAH's attorney advised him to make what he had wanted to be a private agreement between the two of us into a court order. That's what my attorney advised, too, but we both thought STBXAH would never agree to it. We can only surmise that his attorney, much like some of the judges people mention above, is first and foremost concerned about the welfare of the children. Which is as it should be, and makes me feel good about the legal system.